JSFiddle - React, Tailwind, and code Playground

HTML

<link rel="stylesheet" href="http://ajax.googleapis.com/ajax/libs/jqueryui/1.8.4/themes/ui-lightness/jquery-ui.css">
<table>
 <tr>
   <td>col 1</td><td>col2</td>
 </tr>
 <tr id="insert">
   <td>field</td><td>Field 2</td>
 </tr>
 <tr>
   <td>another field</td><td>one more field</td>
 </tr>
</table>

JavaScript

var temp = '<table><tbody><tr>';
var close_temp = '</tr></tbody></table>';
var temp_div = document.createElement('div');


var html_to_insert = '<td>tester</td><td>tester</td>';

temp_div.innerHTML = temp + html_to_insert + close_temp;
insertAfter(document.getElementById("insert"), temp_div.firstChild.firstChild.firstChild);

temp_div.removeChild(temp_div.firstChild);


function insertAfter(target, el) {
    if( !target.nextSibling )
        target.parentNode.appendChild( el );
    else
        target.parentNode.insertBefore( el, target.nextSibling );
};